I expected the Omni logo at the top of the new forum page to take me to the main Omni site but it does not, it simply takes me the forum home page - is this the correct behaviour?
This is indeed the correct behavior.
The Omni logo is as far as I can see the only way to get back to the main forum overview page. If used to get to the Omni site, we’ll need another button for the forum index page.
I agree, but that is the point, perhaps there should be two buttons.